1. Field of the Invention
The invention concerns a connector for connecting a data transmitter and/or receiver to a shielded pair type transmission cable with grounding drain conductor.
2. Description of the Prior Art
The advantages of shielded pair connections are well known and have been exploited for many years in telecommunications. Installed by relatively simple and low cost proven techniques, these links are used to transmit analog and digital signals, in particular over point-to-point links, under good conditions and with good performance.
For this reason they are recommended for local area networks in which they interconnect equipment provided for this purpose with data transmitter and/or receiver equipments connected in exactly the same way to one or more shared links.
Each equipment along a link is connected to an assigned point on the cable constituting the link by means of a connector. In a conventional system the equipments are connected in series.
For reasons including electrical continuity of the conductor wires used to transmit the data and the shielding protecting them against electromagnetic interference, it is necessary to minimize the damage caused to a cable by connecting to it the connectors used to connect the data transmitter/receiver equipments of the data equipment concerned.
This has lead to the design of cables in which all the data transmission wires are surrounded with an electromagnetic shield with which is associated a longitudinal shield continuity drain conductor, galvanically connected to the shield but separable therefrom when the shield must be removed locally to allow connector access to the transmission wires, the drain conductor being adapted to remain intact at the connector and so to ensure electrical continuity of the shield along the cable, despite such local removal.
This has also lead to the development of connectors provided with special terminal blocks such as that described in French patent application No 2647970, to be described briefly hereinafter, enabling the connection of a transmitter and/or receiver equipment by means of a shielded drop and insert cable comprising two pairs of transmission wires to a shielded cable as described above which comprises one pair of transmission wires and a shield continuity drain conductor and which is adapted to have a plurality of transmitter/receiver equipments connected to it in series.
One objective of the present invention is to improve the transmission performance of links fitted with this type of connector by modifying the connectors themselves and in particular by enabling verification of the operational status of the links and consequently of the system comprising them.